Validating a surveillance program of invasive mosquitoes based on citizen science in Hungary

Abstract

Climate change, intensified tourism and trade activity have resulted in several exotic mosquito species invading the temperate zone, with considerable ecological and economic consequences, as well as threats to human health, due to the pathogen-transmitting role of these organisms. Accordingly, three invasive mosquito species (Aedes albopictus, Ae. japonicus and Ae. koreicus) have been described in the last decade in Hungary, a Central European country. It is crucial to understand how invasive species are introduced and their distribution is expanded at the country-level, for which intense surveillance programs are needed. We have established a citizen science program, in which we asked the public to submit reports on their observations of invasive mosquitoes. During a 3-year campaign, we collected and taxonomically validated about 3000 reports that can be arranged along both temporal and spatial scales. We aggregated these observations into 35 km2 quadrats and examined if these can be used for reliable scientific inferences. We first found that the number of validated reports in a quadrat depends on the underlying sampling effort (i.e. number of total reports), but this relationship varies among species and study years. Second, after controlling for study effort, we showed that the prevalence and presence/absence of invasive mosquitoes within quadrats are significantly repeatable among years, but this consistency varies in a species-specific way. Third, we demonstrated that conclusions about the local presence/absence of focal species based on citizen reports corroborate well the results of direct field sampling with conventional trapping protocols. Synthesis and applications: We suggest that if the reporting intensity is appropriate (i.e. the number of reports reaches a species-specific threshold), citizen science results can be used to derive biologically meaningful conclusions about the distribution of invasive mosquitoes in a country. Distribution maps of the three invasive species in Hungary can be used to identify ecological predictors that determine such spatial patterns and also to develop a mosquito control program and assess epidemiological risk.